In the use of continuous filament synthetic textile yarns, it has become increasingly important to overcome the smooth texture of the yarns as initially spun and to obtain an appearance more similar to the natural fibers such as cotton and wool, by a process of texturing or permanently distorting the filaments. Objectives of texturing are to achieve improved bulk, cover, warmth, crisp or soft hand, and, in some instances, to increase the elastic stretch of the filaments. A great variety of methods have been developed to texture the synthetic yarns, among which may be mentioned false twist texturing, knit-de-knit, steam stuffer box crimping, air jet texturing, and gear crimping using crimping wheels. This invention relates to the latter system.
Gear crimping of synthetic filaments consists of passing the filaments through wheels having intermeshing gear teeth which have sufficient peripheral spacing between the teeth to admit the filament without applying any pressure thereto. The crimping wheels may be, but are not necessarily, combined with other yarn processing apparatus such as drawing and twisting apparatus.
A principal difficulty in gear crimping lies in adjusting the spacing between the meshing teeth of the crimping wheels evenly in order to prevent damage to the filaments by pinching of the filaments between the wheels. Previous methods of adjusting the spacing have been tedious and cumbersome due to the fineness of the crimping teeth and the difficulty of making slight adjustments of a gear or crimping wheel on its shaft.
In my copending application Ser. No. 594,938 filed on even date herewith, an apparatus for adjusting the peripheral spacing between the teeth of yarn crimping wheels is described.
In accordance with the invention described therein, a pair of intermeshing gears fixedly attached on separate rotatable parallel shafts drive a pair of intermeshing crimping wheels also fixedly attached on the shafts. The gear and crimping wheel on each shaft are positioned so that rotation of the gear produces similar rotation of the crimping wheel. The number of teeth on each gear preferably is the same, as is the number of the teeth on each crimping wheel, although there usually are several times more crimping teeth than gear teeth. At least one drive shaft may be movable in order to disengage both the gears and crimping wheels.
The relationship between the tooth count of the gears and crimping wheels is such that when the gears and wheels are disengaged and one gear rotated a predetermined amount with respect to the other, reengaging the gears and wheels in the new position will result in a relatively small adjustment of the peripheral spacing between the teeth of the crimping wheels.